Mold for casting test samples



Sept. 8, 1970 H. v. LAWMASTER MOLD FOR CASTING TEST SAMPLES Filed July15, 1968 FIGJ FiG.4

INVENTOR. HOLLY \l LAWMASTEE BY f aw J J J @in M46 Arromvsvs UnitedStates Patent 0 3,527,439 MOLD FOR CASTING TEST SAMPLES Holly V.Lawmaster, 1949 S. Manchester Ave., Apt. 73, Anaheim, Calif. 92802 FiledJuly 15, 1968, Ser. No. 744,859 Int. Cl. B411) 11/60 US. Cl. 249-164 1Claim ABSTRACT OF THE DISCLOSURE A reusable plastic mold for castingcylindrical concrete test samples, the mold including a pair ofcomplementary mold sections which abut and define a cylindrical moldcavity, the outer surface of the mold sections being frusto-conical andfitting within a frusto-conical sleeve having a base. The mold alsoincludes a cover plate for closing the open upper end of the moldcavity, and the assembled mold is upended to enable the sleeve to beupwardly separated from the mold sections so that the mold sections canin turn be separated from the set concrete test sample.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates generally to molds for casting test samples and moreparticularly to reusable, sectional plastic molds for casting testcylinders of concrete, gypsum, and like materials.

Description of the prior art In order to determine the quality andstrength of concrete mixes, it is customary to cast test cylinders andto subject the cylinders to various tests at various stages of settingand curing, including tests of ultimate strength in which the cylindersare tested to destruction. Such tests may be conducted at any time toascertain the quality of the cement, sand and aggregate used inparticular mixes and are particularly helpful in ascertaining thequality of concrete mixes during progressive stages of largeconstruction jobs.

Heretofore, molds for casting such test cylinders have been made ofvarious materials. Some have been made of non-reusable materials such aspaperboard whose consumption is comparatively expensive, or of metalswhich are relatively heavy and have a high initial cost. A mold made oflightweight, reusable plastic is described in US. Letters Patent No.3,163,908, issued Jan. 5, 1965, but that particular mold requiresutilization of a separable base. The joints enabling such separationundesirably provide paths for water leakage, and the separable baseplate arrangement itself is characterized by other problems.

SUMMARY According to the present invention, a mold is provided forcasting test cylinders of concrete and like materials which is ofsectional construction and preferably formed of a lightweight,inexpensive and reusable plastic such as polypropylene. The mold ispreferably of twopart sectional construction with the parts engaged andheld together by a sleeve which is also preferably made of a plastic,such as polyethylene, which has limited flexibility and provides a snugfit over the mold sections to hold them securely in place.

The encompassing sleeve includes an integral lower end wall defining aflat base to support the lower edges of the assembled mold sections whenthey are fitted within the sleeve. A cover plate is provided forengagement upon the upper edges of the assembled mold sections to closethe mold cavity. Once the concrete is set, the

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assembled plastic mold can be upended and the sleeve upwardly separatedfrom the mold sections to enable separation of the mold sections fromthe cast concrete sample. Assuming the cover plate was left in placewhen the mold was upended, the concrete test sample will then be leftresting upon the cover plate.

With this arrangement, the sleeve holding the mold sections together isintegral with the base of the mold cavity so that there are no jointsthrough which water can possibly leak.

Other objects and features of the invention will become apparent fromconsideration of the following description taken inconnection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective ofthe mold according to the present invention;

FIG. 2 is a top plan view of the assembled mold;

FIG. 3 is a vertical sectional view taken on the line 33 of FIG. 2; and

FIG. 4 is a detail view of the encircled area designated by the numeral4 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment of theinvention selected for illustration in the drawing, there are a pair ofmating, complementary mold half sections 11 and 12 which are exactduplicates or mirror images of each other. The mold sections 11 and 12are characterized by vertically oriented edges 13 and 14, respectively,which abut when the sections 11 and 12 are assembled, as best seen inFIG. 4. As will be seen, abutment of the edges 13 and 14 forms acontinuous cylindrical mold cavity.

The internal surfaces of the sections 11 and 12 are preferably trulycylindrical while their outer surfaces have a slight taper so that theouter surface of the assembled mold is slightly frusto-conical.

Surrounding the mold sections 11 and 12 to hold them together inassembled relation is a plastic sleeve 21 having at least its innersurface of frusto-conical form, corresponding to the frusto-conicaltaper of the outside surface of the assembled sections 11 and 12. Thus,the sleeve 21 fits snugly over the mold sections to hold them together,as shown in FIG. 3. Handle grips 22 and 23 are cemented or integrallycast to the outside of the sleeve 21 to facilitate lifting thereof fromthe mold sections after a test sample is cast in the mold. Theperipherally continuous sleeve 21 includes an open upper end forreceiving the mold sections 11 and 12, and also includes an integral,closed lower end which defines a flat base 16. The adjacent upper endsof the mold sections 11 and 12 each includes a peripheral flange 19whose underside rests upon the upper edge of the sleeve 21 when thelower edges of the sections 11 and 12 rest upon the base 16. The flanges19 project radially outwardly of the adjacent edges of the sections 11and 12 to facilitate later separation of the mold components, as will beseen.

A flanged circular cover plate 18 made of resilient plastic materialcloses the open upper end of the mold cavity, the plate 18 engaging theupper edges of the sections 11 and 12, with the flange of the plate 18snapping over the flanges 19 of the assembled mold sections 11 and 12.

When assembling the mold according to the present invention, thesections 11 and 12 are joined together with their vertical edges 13 and14 in abutment, as shown in FIG. 4. The assembled mold sections 11 and12 are then lowered or placed into the interior of the sleeve 21, withthe lower edges of the sections 11 and 12 resting upon the flat base 16,and with the flanges 19 resting upon the upper edge of the sleeve 21.The sleeve 21 securely holds the sections 11 and 12 together, with theparts in the positions shown in FIGS. 2 and 3. The mold is nowcompletely assembled and ready for a test sample to be cast therein.

The concrete or other mix is poured into the cylindrical mold cavity andthe cover plate 18 fitted into position over the assembled mold sections11 and 12 and sleeve 21. After the concrete is cured or set to theextent desired, the cover plate 18 may be removed and the assembled moldupended or turned upside down so that the mold rests upon some suitablefiat surface. The sleeve 21 is separated from the mold sections 11 and12 by grasping the handle grips 22 and 23 and pulling the sleeve 21upwardly, while also stepping upon the portions of the flanges 19 whichproject radially outwardly of the sleeve 21. The mold sections 11 and 12can thereafter be readily stripped away from the cast sample for use ofthe cast sample in testing procedures. The mold parts can then bereassembled for use in casting additional test samples.

The inner surfaces of the sections 11, 12 and the plate 18 being ofsmooth plastic material, the concrete or other material cast thereinwill ordinarily not adhere to the molding surfaces. However it isconventional to place coatings of powder, oil or wax on the moldsurfaces if desired, to insure against any possibility of sticking ofthe mold parts and the cast samples.

The mold parts may be formed of any desired materials but are preferablyof inexpensive, durable, lightweight plastic material and, as anexample, the sections 11 and 12 and the bottom plate 11 may be formed ofpolypropylene. The sleeve 21 is preferably also formed of inexpensive,lightweight and durable plastic material which has some flexibility toinsure a snug fit over the sections 11 and 12, and for these qualitiesan example is a polyethylene plastic material.

The mold according to the present invention is relatively inexpensiveand durable and may be reused many times. It is lightweight for easymanipulation so that the parts may be readily assembled and disassembledin completing the mold and removing the mold parts from the cast sample.

With the sleeve 21 snugly engaging the mold sections 11 and 12substantially throughout their entire length, the mold when assembled isquite strong and rigid. At the same time, the frusto-conical taperedsurfaces by which the sleeve 21 and the sections 11 and 12 engagepermits the ready sliding removal of the sleeve from the mold sectionsin effecting disassembly of the mold parts from about a cast sample.Moreover, the fabrication of the base 16 integral with the remainder ofthe sleeve 21 eliminates any joints in the base so that there is noopportunity for undersirable leakage of water from the test sample outof the mold.

Various modifications and changes may be made with regard to theforegoing detailed description without departing from the spirit of theinvention or the scope of the following claim.

I claim:

1. A reusable plastic mold for casting cylindrical concrete testsamples, said mold comprising:

a pair of complementary mold sections having vertically oriented edgeswhich abut to define a cylindrical mold cavity, the outer surface ofsaid mold sections being frusto-conical upon assembly of said moldsections with said edges in abutment;

a peripherally continuous sleeve substantially the height of said moldsections and having an inner surface of frusto-conical formcorresponding to the frustoconical outer surface of theassembled saidmold sections, said sleeve having an open upper end and a closed lowerend defining a flat base, said assembled mold sections fitting snuglywithin said sleeve and upon said base to hold said mold sectionstogether during casting and setting of a concrete test sample in saidmold cavity; and

a cover plate engaged upon the upper edges of said assembled moldsections to thereby close the open upper end of said mold cavity aftersaid casting of said concrete test sample, said sleeve, subsequentupending of the plastic mold, being upwardly separable from said moldsections whereby said mold sections can be removed from the set concretetest sample.

References Cited D. W. JONES, Assistant Examiner U.S. Cl. X.R.

